Rendering cooker



May 1, 1951 c. J.`MERR|MAN ETAL REDERING cooKER .'5 Sheets-Sheet 3 FiledJune 21. 1947 Patented May 1, 1951 UNITED o STATESv OFF ICE 2;'551,034'RENDERING cooKER 'Charles J. Merriman, Boston,`M`ass., and AlfredP.

"Hucli'berger, N ew'Yor'k, N. Y., assignorsto Con- Vsolidated RenderingCompany, Boston; '-Massi., .a corporation of Maine Application June .21,1947,,.Serial No, 756,240

7 o1aims. (cl. 28-280) This invention relates to improvements in amethod and means for processing animal and fish materials. It has to doWith the rendering or melting of fat-bearing and oil-'bearing edible andinedible animal matter and dehydratingby-products of the livestockslaughtering and fishing industries. ,More especially the inventionprovides for the determination of the point at which the processingshould cease and for stopping the process when such point is reached.The invention is hereinafter particularly described in its' The 'mass of'raw'material 'is promptly'placed fin.

a large cylindrical 'tankyariously called a cooker, `a fat melter 'or a"dryer, 'but hereinafter `referred to :as a 'c'ookerf' and subjected toheat in the neighb'orhood of 220 F; While under the influence of thisheat the mass of material in the cocker must be continuously agitated.'If it were permitted to rest'undisturbed 'in 'the cooker it would soonadhere to the wall thereof and .become burned. 'The layer next adjacentthe wall would of course vbe the first to burn but this dami agedcondition would gradually proceed through the mass if the heat Werecontinued. By agitating the mass While exposed tothe heat it iscontinuously swept along the surface of the cocker 'and intermixed Withitself until such time as the end of the cooking operation approaches.:In the treatment of animal materials this constantstirring of 'the massin the cooker enables the fat in liquid form to separate from theremainder. To an extent this liquid fat can be drawn off Afrom thecooker'while 'the dehydratingis taking place.

`If the cooking is not carried to thevproper point, hereinafter referredto as .the end ;pointf' ;the quantity vof fat obtained from 'thematerial will be'less than 'it shouldhe, there Will remain lin the massan undesi'red resiiiue ofliquid fat and after the mass has'beensub'jected to pressure' upon removal 'from the cocker the finalremaind'er'in then solid calge form will still contain excess fat andhave a smaller proportion of the protein content which determines itssalable value for use in the preparation of animal feeds;

AIf the cooking is continued beyond the properl end point, suchovercookingof the mass causes some of the fat 'to become "'set" or fixedin 'the solid portions ,of 'the mass thus again producing in the finalcake form a remainderv which is of less ofthe'operator attending'to 'thecookinjg. As

point 'has' =been neared', 'the operatorV would, take a small sample'`'of the mass Afrom the cooker and' feel 'of 'it `between vvhi`s'fingers.According to its "feel 'he would decide whether'it should be 'furthercooked or not. 4Since the decision thus' rested solely upon the jndgmentof the operator, the cook'ingv of 'the material would' vary inaccordance with each loperator's own personal judgment and even the same;operator Would not be entirely consistent in'hisludgment of the severalcooking Operations 'per'fQrmed' during his tour of duty.

'The cooking or rendering operation varies depending upon the nature. ofthe material being oooked, particularly its mo'isture content, theamount of heat' and the'length of time it is applied and, as ,notedabove, the Judgment of the man 'in'charge of the cooker. 'The supply ofjheat caniby modern controls bekept substantia'lly unif form,sufiicientlyso so 'that thisfactorcan be considered as no longer Vamajor influence. material' be cooked mustloe taken as de'livered 'to'the processing plant and 'heretofore the iudg- But thel whereby theproper end point of the cooking process shall be determined by thechanging condition of the material itself, thereby eliminating thejudgment of the operator entirely. The improved method involves acontinuous testing of the material while in the cooker, this testingbeing done by presenting to a fixed terminal within the cookerconstantly changing samples of the material undergo-ing the heattreatment. This continuity of testing constantly changing samples ismost important because of the non-uniformity of the moisture contentinthe material being processed which continues almost up to the end point.It is the final desired moisture content` ularly positioned in thecooker so that it will4 be exposed to continually changing samples ofthe material, an electric circuit comprising said terminal and includingan instrument which is responsive to changes in the current flow due tothe changing resistance of the material being dehydrated, and controlmeans actuated by the instrument for terminating the cooking operati'on.Other features of the invention will become' apparent as the detaileddescription hereinafter is developed. v

Another objectionable point of the practice heretofore has been thedifiiculty of supervising the work of the operators in charge of thecookers. In a processing plant the cookers are frequently located insome room remote from the superintendent's office. He has had no way of.telling from his office whether or not the cooking process is beingcarefully Watched. The present invention contemplates that the progressof the cooking operation shall be at all times indicated in thesuperintendent's office, and that the sequence of events leading to thestopping of the cooking operation shall be initiated from that place.The invention also provides for giving signals in the superintendentsoffice to show that the-cooking operation has been terminated, thatthe'discharge of the cooker has been started, and that the system hasbeen reset for the carrying oi'r'of 'the successive cooking operation.Moreover, the invention further providesthat simultaneously with thetermination of the cooking operation that fact shall be announced to theman'in charge of the cooker by an audible or visible signal in hisvicinity.

:The best mode in which it has been contemplated to apply the principlesof the present invention is shown in the accompanying drawings but theseare to be taken as illustrative because it'is intended that the patentshall cover by suitable expression in the appended claims whateverfeatures of patentable novelty are disclosed in the invention as awhole.

jIn the accompanying drawings:

Fig. 1 is a somewhat diagrammatic showing of `illustrative apparatusembodying the improved structural features of the invention and capableof practicing the improved method;

Fig. 2 is an elevation of a medial section of a cooker, and drivingmeans, used in the dehydrating'and rendering Operations, showing theimproved terminal within the cooker;

fFig. 3 is an elevation in section, taken as on line 3-3 of Fig. 2;

Fig. 4 is an elevation of the head end of the cooker;

improved means for practicing this Fig. 5 is a diagrammatic layout ofthe electrical circuits of the improved apparatus;

Fig. 6 is plan view of the novel terminal and coupling; and

Fig. 7 is a sectional view thereof taken as on line 1-1 of Fig. 6.

Referring now to the drawings, and more especially to Fig. 1 which showssomewhat diagrammatically the apparatus associated with the cookingoperation, the material to be processed is brought to an upper floor Hiin proximity to an inlet duct l2 which leads downward to one end of acooker Ill. In charging the cooker the material is put into the duet 12and falls therethrough into the cooker and is then spread along theinner bottom wall thereof as will later be described. When a charge isin the cooker ready for processing, the entrance to the inlet duct isclosed by a suitable cover l because, as will also appear later, apartial vacuum is set up in the cooker during the cooking operation.

A valve l8 is opened to admit steam to a pipe 20 which has severalconnections 20a with an annular space 22 (see Fig. 2) between an innercylindricalv shell 24 and an outer cylindrical shell 26 joined at theirends to circular closure plates 28 and 30. Steam at a temperature of 220F. and upwards is continuously fed to this space 22 while the cooking isin progress. As the heat is transferred to the material in the cooker,the condensate fiows out of several outlets 32 at the bottom of thecooker which have connection 33 with a suitable steam trap 34.

vWith the cooker thus at proper temperature, avconstant speed motor 36is started. This motor is connected by suitable gearing means 38 With ashaft Mi which is journaled in bearings 132 supported by brackets 44mounted on the end plates 28 and 3G. The end portions of this shaft arecylindrical and extend through suitable stufiing boxes 46 at the axis ofthe cooker. Within the latter the shaft is preferably of rectangularcross section (see Fig. 3) and to it are secured a series of agitators48.

The preferred form of agitator comprises two arms 48a and 48h, (see Fig.3), each extending in a generally radial direction from a V-shaped hubmember 48a and 48d. These hub members are bolted together and clamp thesquare shaft 40 tightly between them. The blades 48a and ll8 at the endsof the arms are particularly formed. On one side the blade has a flatface 48g which is set at substantially a right angle to the forward pathof travel of the blade as it rotates within the cooker. The other sideof the blade has a curved surface 48h so disposed that when the blade ismoved in the reverse direction this curved surface acts as a sort ofplough to move the material in the cooker toward the discharge endthereof. These curv'ed surfaces of the blades are also used to spread afresh charge of materialalong the bottom of the cooker when it isreceived from the inlet duct |2 (see Fig. 2). When turning in theforward direction during the cooking operation, the flat faces 48g (seeFig. 3) of the blades push the material ahead of them formingmomentarily behind a blade a sort of trough into which the materialfalls to be intermixed with itself. This constant agitation of thematerial causes the mass to move about from side to side and from end toend of the cooker in a general stirring which is not only beneficial butnecessary for the successful cooking of the material being processed.

When animal material is being simultaneously dehydrated 'and renderedthe .constant application of heat thereto separates part of `the fat inliquid formy from the more .or less solid portions of vthe mass. more.volatile liquid or moisture in the mass is converted .into a vaporwhich leaves the cocker through an outlet duet :(see Fig. 2)- leading toia condenser (-not shown). VThe greatest part` of this fluid dischargeis water vapor and as it reaches the condenser and is condensed a.partial Vacuum is set up in the cocker which augments the escape of thevapors. As the fat rendered from the material in the cocker assumes aliquid condition some of it can. be drawn oif through a screened outlet52 l(see Eig. 3) lin the head end 30` .(see Fig. 2) of .the .cocker andconducted through a pipe 54 (see Fig. 3) .to a collecting tank 55L.('see Fig. 1) below the floor '58. on which the cocker standS.

At a particular point in the processing operation the volatile moisturein the mass will have been substantially all distilled off and at vthatsame point the maximum yield of product .both

During the cooking operation the as to yquantity and quality will hatebeen attained.

At that ppint the cooking should be brought to anend and the materialremaining in the cooker promptly removed therefrom.

This removal is accomplished by turning the motor 36 and agitators (seeFig. 2) in the reverse direction of rotation. As previously describedthe curved surfaces 43h of the agitator blades. are so shaped that whileturnin'g in the reverse direction they move the material in the cockertoward and through va diseharge opening 60 at the bottom side of thehead end. of the cocker. The discharged material falls into a hopper 52(see Fig. 1) having a. perforated bottom through which more of theliquid fat drains into a suitable receptacle 34 having a connection withthe collecting tank 5G. From the hopper 62 the undrained portion of the.material is placed in a press .E58 and subjected to suiiicient pressureto squeeze out the remaining fat which passes through a strainer (notshown) and then-ce through a pipe l to the collecting tank .55. The hardpressed cake of solid matter remaining in the'press is then reinoved andsold for use in the preparation of peultry feed or other animal foods.From the collecting tank 56 the fat-is fed into drums, tank trucks ortank cars for transporatation to its place of subsequent use.

As stated earlier the most important step in this dehydrating process,and likewise in the rendering of animal material, is the precise deitermination of the end point of the cooking oper-ation and the Steppingof the cooking when that point is reached. It has been dscovered thatthe determination of the end point can bo made by a Constant samplin'gof the material as it is being oooked to find out when substantiallyallthe volatiie matter has been removed. It'jhas also been found thatthe amount of moisture cr volatile matter in the material has a directrelation to the resistance of the material to the passage of an electriccurrent through it. Accordingly, the improved method herein disclosedcomprises passing a current through continuously changing samples of thematerial while it is being agitated in the cocker and the volatilematter is being removed. As the volatile matter leaves the masstheresistance of the remaining material increases and when somepredetermined point is reached, which in fact is the point at which themajor portion of the volatile moisture has been liberated from thematerial, the cooking operation is. .abrupt-ly 'terminated This'prortipt'A cessa'tion .of :the -cooking is- 'accomplished by theimproved. control apparatus disclosed herein.

- .One of the .principal' .elements in .this apparatus is za singleterminal, generally numbered 12., which: is used for making contact withthechanging samples of the material. The .preferred form of .terminalisshown in Figs. 6 and 7., and has been found to .be most satisfactory.It comprises a 'central :plate 12a of metal having ,a high. coeificientof conductivity. Thisv plate is embedded ina sort of .cylindrical'plug12h .of nonconducting material with the .outer surfaceof the plate 12afully .exposedl This insulating plug is in turn surrounded :by a ring'lc of metal Whose outei` cylindrical surface is` threaded .so that the.assembly as. a whole can be .screwed into a suitabl'y threaded hole in.the inner end of a tubular coupl'ing .7M (see Fig.. 3) which extendsfrom the outer shell of the cocker through the steam space .to :theinner shell of .thecooken This coupling iswelded tightly to both shellsandv when. the terminal is screwed into the coupling, the wholeconnection is perfectly tight. A ring 'i2d (see Fig. '7) 'of metalofhigh conductivity is also embedded partly in the dielectric 1.21) and.partly inV the outer ring Mc, being preferably screwed into the latter.v

The inner faces of the central plate 12a `and the ring 72a aresubstantial'ly flush with the surface of the inner shell and .alwaysavailable for contact with. the material being cooled.

The terminal 12 is placed about one-sixth of the .distance from thedischarge end 30 (see Fig.

2) to .the inlet end 28 of the. cocker and about thirtyl degrees aroundthe circumference of theV cocker from its lowermost longitudinalelement, and .directly under or opposite the path of one of therevolving agitators. As' this agitator revolves. one of its bladespnshes a. portion of the material across. the terminal and then:promptly thereafter the other blade Vlikewise pushes a different portionof the material across the terminal. These successive portions of thematerial are herein called. samples and thus it follows that theterminal is subjected to continually changing. samples of the material.Between the. approach of one blade and then, the other with theirdifferent samples, the terminal is, of. course, in contact with thematerial which for the moment is adjacent to it, butit is the recurringcontact between. the terminal and the moving samples. that insures theproper testing of the material..

'Because if the material wasnot being agitated, thelayer closest to thewall of the cocker wouldpromptly become completely dehydrated and,indeed would soon. become burned. If this layer were in contact withthe. terminal, its freedom. from all vol'atile moisture would give it ahigh. degree' of resistivity, indicating that the .cooking process: wasat an end, whereas under` the assumed conditions the .greater portion ofthe material vwould still be very moist and relatively uncooked. Thus itis highly essential that the material be kept in Constant agitation.This, of

course.. assists in the liberation of the moisture although it is anobserved fact that certain portions of the material seem to retain theirmoisture much longer than do other portions. In-

gdeed, it is. not uncommon, evenwhen the end of a cookfiing operation.is near, to have a sample of still. quite moist material sweep across.the Such a sample would be relatively low in resistivity Vandthisjmightxmislead. an observer' 75 asto the general condition of the;material asv terminal.

a whole. ut such a sample is only one of many being presented to theterminal and thus it is that despite the great change in resistance thatmomentarily occurs, the continuity of the changing samples enables thecontrol means to be actuated by what might be termed the averagecondition of the material.

The improved control means comprises an instrument 16 (see Fig. 1) whichis preferably located in the ofiice of the plant superintendent and iselectrically connected with the terminal 12 and with a control cabinet18 near the cocker, from which cabinet circuits lead to the motor 36, toa solenoid 19 associated with the steam valve 18, and to alarm devicessuch as a bell 80 and a lamp 81. The diagrammatic representation of thecontrol system is shown in Fig. 5.

As shown in Fig. 5, the entire control system is inactive, the motor 36is idle, and the steam valve 18 is closed. The usual domestic supply ofcurrent is received via the wires 82 and 84 when the switch 85 is closedas it normally is.

A Wire 86 leads from the supply line wire 82 to a signal lamp 81 whichis located at the instrument and shows when lighted a distinguishingcolor, such as white, to an observer in the superintendentis ofiice.From this lamp 81 a Wire 88 runs through the primary windings of threeinduction coils 89, 98 and 91. From the last coil a wire 92 runs to arelay 93 from which a Wire extends to a switch 94 whence a Wire 95 runsto the other supply line wire 84. This switch 94 will be hereinafterreferred to as the reset switch It is spring actuated to open positionbut when closed manually it is engaged by a latch 96 which retains theswitch closed until the latch is released as will later appear. When theswitch 94 is closed current flows through the lamp 81, the primarywindings of the three induction coils 89, 98 and 9|, and through therelay 93, energizing the latter and effecting closure of a switch 98 ina circuit presently to be described.

A low Voltage current induced in the secondary winding of coil 89 flowsalong a circuitiwhich comprises a Wire 100, an adjustable standardizedresistor 1112, and a Wire 104 leading to the central plate 12a in thecooler. As hereinbefore described the current fiow passes from thisplate 12aI through the material being dehydrated and thence into thering 12d and through the shell of the cocker to ground. A wire 186 fromthe coil 89 is also grounded at 101 within the instrument. Thus thecircuit between the instrument 16 and the cooker is completed throughthe ground.

The Variation in the amount of current flowing along the Wire 184depends entirely upon the resistance encountered by the current duringits passage through the samples of the material in the cocker. If thismaterial is very moist, as it is when first placed in the cocker, theresistance to the flow is relatively very low. As the moisture isvolatilized and leaves the mass of material the resistance of theremaining material becomes increasingly greater. Since the .voltageremains constant it follows that as the resistance increases the flow ofcurrent decreases. This change in current flow is utilized to affect themovement of a pointer 108a in a meter 108 which for purpose ofindication is preferably calibrated in terms of the resistance. That isto say, the scale on the meter along which the end of the pointer 1118amoves has its graduations marked in terms of resistance rather than interms of current flow. When the current flow is greatest, which meansthe resistance in the material is low, or that no material is bridgingthe annular space between the plate 12a and the ring 12d, the pointer108a will be at the low end of the scale on the meter. As the currentflow diminishes, which means the resistance is increasing, the pointerswings clockwise toward the higher reading end of the scale.

Connected to the wire 104 is a wire 1 111 leading to the grid 1 12 of anelectronic tube 1 14. Another Wire 116 leads from Wire 11'16 through aresistor 111 to one end of a solenoid (not shown) in the meter 1118. Awire 118, including a resistor 118a, is connected across the wires and116 and from the Wire 116 a connection 121i is made through a resistor121m to the cathode 122 of the tube 114. A connection 124 leads from theplate 126 of the tube through a condenser 124a and thence through arectifier 124b to the other end of the solenoid in the meter 1118.Around the meter is a protective shunt connection 128 including acondenser 18a. The filament circuit through the tube is from theinduction coil 90 through wire 130 and thence along the connection 1211to the cathode 122, and from connection 124 through a Wire 132 and aresistor 132a to the coil 90. All of which serves to transmit a currentflow through the solenoid of meter 198 which corresponds to the fiow ofcurrent through the samples of material in the cooker.

Let it be assumed that material is in the cocker ready to be processed.The agitators 48 must now be driven in their forward direction ofrotation and the steam valve 18 must be opened. With the switch 85closed, as it usually is, the man in charge of the cooker manuallycloses the reset switch 94 to establish flow through the primarywindings of the coils 89, 913 and 9| of the instrument 16 and alsothrough the lamp 81 which, when lighted, indicates that the instrumentis active. The initial lighting of this lamp 81 also indicates in thesuperintendent's cfiice that the man at the cocker is about to start thecooking operation.

He does this by moving a lever 184 of a reversing switch 132 to the'*forward" position and thereby connects the wires 136, 138 and 14D withwires 142, 144 and 146 respectively which lead to the commutator brushes148, 158 and 152 of the motor 35. The operator then moves a lever 154 ofa switch 158 to its "start" position. This connects the power line wires158, 161i and 162 with wires' 164, 168 and 168 respectively which inturn are connected by wires 118, 112 and 114 with the wires 136, 138 and1411. The operator must hold the lever 154 in its "start positionbecause suitable spring means in the switch assembly always tend toreturn the lever 154 to its neutral position shown in the drawing. Afterthe motor 36 has thus seen started and has reached its nermal speed, theoperator then throws the lever 154 to its "run position. In thisposition, the wires 158, 168 and 162 are also connected through theswitch 156 to the wires 164, 166 and 158.

When the lever 154 is moved to its ('run" position an arm 154x on thelever engages a switch 116 (which is held in its open position by atension spring 118), and closes it. The arm 154a is at the same timeengaged by a latch 18D which holds the lever 154 in its run position.This action fasu'nou Wire 185 that has two branches` v1.85ai'and-1.8511.The branch 185a leads to' the switch 9.8 associated with the relay 93and the branch. 1851 leads to a switch 1131` associatedwith'anotherrelay 18'1 whose functionswill later appear. From the switches 98 and186 two branches 1880.' and 188b respectively lead through a -wire 1.88'to a relay 189. From the latter a Wire' 199 goes to the switch 1'16 andfrom this switch another Wire 192 runs tov another relay 194 from whicha wire 196 leads to the other supply line Wire-'84.

Upon the closing of switch `1 `16by the lever arm 154a (the switches 184and 98 being 'already closed), the relay 189 is energized toswing thelatch 180 into engagement With the lever Va'rn'i z.

154a. and hold -the lever 1'54 in--its rur-1" position. Thus theagitators are'V driven in' their forwardf' direction of rotation.

The simultaneous energization of relay 1.-94, upon the closing of switch116, closes another switch 198. This latter switch is partof' a circuitcomprising a wire 299 leading fromthe supply line wire 82, a wire 2112running from the switch 198 to theV solenoid '19 ofv the steam valve 18,a Wire 204. leading to a normally closed contact arm 205a of the tripleswitch 205, and a Wire 2.86 running to the other supply line wire 84.This triple switch 205 has two other arms 2.6.51) and. 2650 which are intheir open positions when the arm 205a is in its closed position. Theswitch is held in this described position by a compression spring 29'1.The closingof switch. 198 effects the opening of the steam valve 18 andthus heat. vis supplied to the material in the cocker. 5 The apparatusisnow effective to carry on th cooking. operation. The agitators areturning. and continually moving samples of the material `'in the cockeracross the terminal '12 and thev steam is supplying heat to the materialto affect' its .dehydration and, if the material is of animal Origin,the rendering thereof is taking place. When the liquid fat reaches alevel above the screened outlet .5.2 (see Fig. 3) a valve 54a in thepipe .54 can be opened and the fat drained off into the `collecting tank56 (see Fig. l). The Weightof this liquid fat is sufficient to overcomethe partial' vacuum in the cocker and so the fat can flow from thecocker .until its level is ,back to .that of the screened outlet 52 (seeFig. 3). Whereup-on the valve 54a is again closed. As thel volatilemoisture leaves the material in the cocker, the resistance of theremaining mass increases and, as previously stated, When the dehydrationhas reached the desired point, the resistance to flow of the currentthrough the material will be at a predetermined point indicated by theposition of the pointer IIJBa (see Fig. 5) of the meter 108.

At this point, the cooking operation is abruptly terminated as follows.Thepointer 11J8a will close a switch 288 in the meter 198. This switchis part of a circuit which comprises a Wire 218 leading from the coil 91to the switch 258, a Wire 212 connected to a lamp 213 on the instrument'16, a Wire 214 from the lamp to a relay 21,5, and a Wire 216 running tothe coil 9,1. This lamp 213,

when lighted, should show a distinguishingcolor from that of lamp 81.Closing of the switch 298 energizes the relay 215 and brings about theclosing of another switch 21-8. This latter switch is part of a Circuitccmprising a Wire 226 from the supplyV line wire 82, a Wire 222 leadingfrom circuit just described, both relays 224 and 228 are energized andthe lamp 213 is lighted to indicate in the superintendentys office thatthe cooking operation has ended. At the same time the man at the cockeris likewise informed because the energized relay 224 closes a switch 232which is part of a circuit comprising a wire 234 connected With thesupply line wire 82, a Wire 236 running from the switch 232 to a bell89, a Wire 238 from the bell to the lamp 81 and another Wire 249 runningto the other supply line Wire 84. The closing of switch 232 thus bringsabout the giving of both an audible and a visible signal to the man incharge of the cocker.

This ending of the :cooking operation is accomplished, simultaneously'with the giving of the signals, because ofv the energization of therelay 228. When this occurs the switch 184 is opened thus breaking thecircuit through the relay 189. The consequent deenergization of thisrelay releases the latch 188 and allows. the lever 154 to` return to itsneutral position and thus break the power connection to the motor 36which thereupon stops and the agitators are brought to rest. The openingof the switch 184 alsov causes the relay 194 to be deenergized, thuspermitting the steam valve 18 to close and' cut off the supply of steamto the cocker. The latter does not greatly cool' down because the steamremaining in the space 22 (see Fig. 2) 'between the shells of the cockercontinues to be condensed and give up'v heat. This is desira'ble whenthe material being processed is animal material because it keeps the'fat Vin the liquid` state-while the material is being removed` from thecocker.

Upon` being advised by the signals that the cooking operation has beenended', the operator thereupon opens the door'a (see Fig.'2) at -thedischarge outlet and then goes to the control cabinet '18- (see Fig. l).He-first throws the'zreversingV switch lever 134 '('see Fig. 5) toits-f-'reiverse position. This will change' the connections between the`power line wires 136 and 1.'40 so that now they will' be connectedwiththe brushes. 152 and 148 respectively, thereby preparing the motorcircuitfor reverse'rotationV of the motor. In moving the lever '134 toits reverse position an arm- 134a' on the lever engages the tripleswitch 205 and -moves'its contact arm 205a to its open position and atthesame time moves its other two contact arms 2951' and 2850 to theirlosed positions. The'movement of Ihe contact arm 21l5a has no immediateeffect,. since the switch 198 of the .circuit through this contact armhas already been opened as previously described. But the4 opening ofthis contact arm 2050; does preventv the opening of the vsteam valve 18even though the. switch. 1-9iis again closed as will presently appear.V

The movement of. the contact arms 2051 and 205 .c to their closedpositions `estahlishes two different circuits. The .arm 2,9510. Controls.a pircuit comprising a .Wire 242 leading from a supply line Wire 82a toa relay 244, a Wire 2.45 .from this relay tov the contact armv 29.50,and a Wire 248 from the latter arm to another supply line Wire 84a. Therelay 244,,controls the latch 915 and therefore upon the closng of thelcontact arm 295cand the consequent energization of relay 244, the latch96. is withdrawn from the reset switch 94. which. thereupon moves to itsopen position under .the pull of a. spring 259. The opening of theVreset switch 94 breaks .the circuit thrquehpth instrument thusrendering-it in-.- active. This .results in both lampls .81 and 213*being extinguished which indicates in the superintendent's office thatthe cooker operator has initiated the reverse or clearing action of theagitators 48. Moreover, while the switch 132 is set for reverse movementof the agitators, the reset switch cannot be held in vclosed position bythe latch 96 because of the energization of the relay 2M.. Thus thecontinuous lighting of `'the lamp 8'1 cannot occur while the discharge'and loading of the cooker takes place.

'The deenergization of the solenoid in the 'meter 108 allows the switchv208 to open and 'overcome the tendency of the pointer I 08a to keep itclosed. With the instrument 'F8 thus out of control, the relay 215 isdeenergized and, as a 'consequence, relays 2211 and 228 are likewisedeenergized. The resulting opening of switch 232 cuts off the signaldevices 80 and 81. The deenergization of relay 228 permits switch 184 toreturn to its normally closed position, although this has no immediateeffect because as previously described the switch 1'16 has been opened.

The closing of contact arm 205D, simultaneously With the closing ofcontact arm 205c,

.establishes another cirouit which comprises a Wire 252 running from thesupply line wire 82a vto the relay 18'1, a wire 2511 thence to thecontact |arm 205b, and a Wire 256 to the other supply line .Wire 84a.The closing of this circuit by the movement of the contact arm 205b toits closed posi- Ation energizes` the relay 181 and thereby effects theclosing of the switch 188. This has no immediate effect because theswitch 1 '16 is open, but the closing of the switch 186 does prepare forsubseqfuent current flow along the Wire 182 through the closed switch184, along wire 185 and its branch 185b to the now closed switch 188,thence along the branch 188b and wire 188 to relay 189 and along Wire190 to the switch 116.

The operator now throws the lever 154 to its "start" position and thento its "run" position. As before this starts the motor turning (now inthe reverse direction) and as the lever 154 is swung to its "run"position, the switch 1'18 is vagain closed by the arm 154a, and therelay 189 is energized to cause latch 180 to engage the lever 154 andhold it in its urun" position. Of course, the closure of switch 1'18also re-energizes the relay 194 and closes the switch 198, but this hasno effect on the cirouit through the steam valve solenoid '18 becausethe contact arm 205a of the triple switch 205 is still in its openposition. Consequently although the motor is running in its reversedirection, there is no steam being supplied to the cooker.

During this reverse movement of the agitators the material remaining inthe cooker is pushed toward and out of the opening 60 (see Fig. 2) untilthe cooker has been cleared. The operator then closes the door 60a andnotifies the men on the floor above that the cooker is ready for a newvcharge and this is put into the cooker through the inlet duct 12. Thiswould pile up at the entrance end of the cooker were it not for thecontinued rotation of the agitators in the reverse direction. Because ofthis the new charge is fed along the cooker until it is more or lessdistributed therein and some of it approaches the opening 80.

When the cooker has thus been charged, the operator goes to the cabinet'18 (see Fig. l) and by means of a manual handle 280 (see Fig. 5)releases the latch 180. Incidentally this handle 280 has a connectionwith an external handle .260a (see Fig. l) by which the motor can bestopped at any time in case of an emergency. This release of the latch180 (see Fig. 5) and the consequent return of the lever 154 to itsneutral position effects the opening of switch 118 and the opening ofswitch 198 but nothing more immediately follows because the latch 180was manually released and the cirouit through the steam valve solenoid'18 was already broken because of the open contact arm 205a of thetriple switch 205.

The operator next throws the lever 134 of the reversing switch 132 backto its "forward position, and thus removes its arm 13=ia from engagementwith the triple switch 205, allowing its contact arm 205a to return toits closed position and the arms 205D and 2050 to return to their openpositions. The closure of the contact arm 205a has no effect on thecirouit through the steam valve solenoid '18 because the switch 198 isopen.

The opening of the contact arm 2051) breaks the cirouit through therelay 181 and allows switch 188 to open, and the opening of the contactarm 2050 deenergizes the relay 244 and permits the latch 96 to return toits position where it can engage and hold the reset switch 94 closedtor. In case he should attempt to start the agitators without closingthe reset switch 911, he could not do so because the latch would notengage the arm 154a of the lever 154 and the latter would return to itsneutral position. This is due to the fact that both switches 98 and1812` are open and the relay 189 is not energized. Therefore, before thenext cooking operation can be started the operator must manually closethe reset switch 94. As previously described this isheld closed by thelatch 98 and the resulting current fiow through relay 93 closes theswitch 98 so that the relay 189 will be energized to hold the lever inits said position rupon the closing of switch 1'16 by movement of thelever 154 to its "run position.

The closing of the reset switch 94 by the cooker operator restores theinstrument 16 to activity and this is indicated in the superintendentlsoffice by the lighting of lamp 8'1. The lamp 213 will not be relighted,however, because the fresh material put into the cooker and moved alongtoward its discharge end has placed some of the material in contact withthe terminal '12. This material is so moist and its resistance to fiowof the current through it is so low that upon the reenergization of theinstrument the fiow of current along wire 104 is great enough to returnthe pointer promptly to the lower end of its scale and at a positionremote from the switch 208v This completes the cycles of operation andthe operator can at once proceed to throw the switch 154 to its "startposition to initiate another cooking operation.

Although the performance of the cooker and `the control devices havebeen described more particularly for both the dehydrating and renderingof animal material, the operation is substantially the same when thematerial being processed is fish material. Ordinarily no renderingoccurs when fish material is in the cooker and so there is no opening ofthe valve 54a (see Fig. 3). In. some instances, however, with certainkinds of fish material oil can be extracted, in which case the wholeoperation proceeds just the same as when animal material is being bothdehydrated and rendered.

We claim:

1.` The combination with a cooker for rendering material, having a'fixedinner cylindrcal 'ananasa ,13 .'shell, a rotatable shaft centrallydisposed 'within said' shellxwith agitator blad'es mcunted 'thereon soas to wipe around' close by the bottom wall of said shell, la. motorhaving driving connection with said shaft, a power circuit to saidmotor, -a

manually operated switch in said circuit which tends to assume an openposition, a latch` for holding saidl motor switch closed, of controlmeans comprising an auxiliary circuit having a normally' open switchtherein in position tol be closed by the manual closing of thev motorcircuit switch and having a ncr-mally vclosed- -switch,

vclosed switch and thereby deenergizing the first mentioned solencid torelease said latch, and a third auxiliary circuit for effecting theenergization of the second mentioned sclencid, the said third auxiliarycircuit comprising a connection with said inner shell and anotherconnection `with an insulated terminal mcunted in said inner shell insuch spaced relation thereto that the space between them is spanned bycontinually changing samples of the` material being rendered whereby themoisture in said samplesV acts as a conductor between said terminal andsaid shell, the amount of current fl'ow. in said third circuit being inacccrdancewith the moisture content ofl said current conductingsamples,l and 'a device in said third circuit responsive'- when thecurrent fiow through the said samplescorresponds tc 4a predeterminedmoisture: content therein to effect the energization of said. .secondcircuit and therebybring about the d'eener'gi'zation of the` first' saidauxil'iary circuitl'and the opening of said vmotor switch. I

2. The combination with a cocker for render- 'ing material to a desired'end point, having inner and outer cylindrical shells with an annularspace therebetween, a rotatable shaft centrally positioned within saidshells having agitator blades mounted thereon so asV to wipe portions ofthe material along the bottom wall of the inner shell, a flow connectionbetween said space and a supply of steam, a valvein said connection, amotor attached to said shaft, and a power circuit for' said motor, ofcontrol ap'para'tus for controlling' the operation of said motor andsaid valve comprising a main switch in said power circuit, an auxiliarycircuit having switching means therein closed byi the closing of saidmain switch, relay means in saidv auxiliary circuit energized upon the'closing of said switching means to hold said main switch closed and thesaid valve open; a second auxiliary Circuit normally open and having arelay therein capable upon being energized to effect the opening of thefirstv said auxiliary circuit and thereby deenergizing its said relaymeans; and a vthird auxili'ary circuit comprising a connection with theinner shell of said cocker and a connection with an immovable terminalmounted in said 'inner shell, insulated therefrom, and so positionedwith respect to said shell that ccntinually changing samples of thematerial` being rendered make contact simultaneously with the shell and"said fit Vtill samples, and a relayv in. said third circuit acting uponthe current fiow therein corresponding to a predetermined end pointcondition of said material tc effect closure of the said second circuitand thereby energize the relay in said second circuit and bring aboutthe opening of the first said circuit with consequent de-energization ofits said relay means Whereby the motor is stopped and the steam valve isclosed;

3. The combination with a cocker ccntaining a charge of material to berendered, having fixed inner and outer cylindrical shells with anannular space therebetween, a rotatable shaft centrally dispcsed withinsaid shells with agitator blades mounted thereon so as to wipe aroundthe inner shell close =by its bottom wall, an electric motor for drivingsaid shaft, a power circuit connected to said motor, a main switch insaid power circuit, a fiuid flow connection between said annular spaceand a supply of steam, and a valve in said fl'uid fiow connection forcontrolling the fiow of steam therethrough, of control means responsiveto a predetermined condition of said material for sto'pping said motorand closing said steam valve when said predetermined condition of thematerial being rendered is reached; said control means comprising'releasable means for holding said main switch closed during therendering operation of the cocker, a sclenoid effective when energizedfor holding said steam valve open, a control circuit including switchingmeans held closed during the rendering operation for retain- Ving thesaid releasable means: in motor Operating position and for maintainingsaid sclenoid energized, and another control circuit including saidinner shell and an immovable terminal insulatecl from said shell inposition for continually changing samples of the material being renderedto be in contact with the said terminal and said Shell "V simultaneouslywhereby current is conducted between the terminal and said shell by themoisture content of said samples, the current fiow thus conducted beingproportional to the moisture content of said material samples, and meansin the last said control circuit responsive to the current flow thereincorresponding to the said predetermined condition of the material foreffecting the opening of the said switching means in the first saidcontrol circuit to thereby effect the opening of said main switch andthe de-energization of said solenoid whereby the said motor is stoppedand the steam valve is closed.

4. The combination with a cocker containing a charge of material to berendered, having fixed inner and outer cylindrical shells with anannular space therebetween, a rotatable shaft centrally disposed withinsaid shells with agitator blades mounted thereon so as to wipe aroundthe inner shell close by its bottom wall, an electric motor for' drivingsaid shaft, a power circuit connected to saidimctor, a main switch insaid power circuit,

`a fluid flow connection between said annular space and a supply ofsteam, and a valve in said fiuid flow connection for controlling theflow of steam therethrough, of control means responsive to apredetermined condition of said material for stopping said motor,closing said steam valve and giving a signal when `said predeterminedcondition of the material being rendered is reached; said control meanscomprising releasable means for holding said main switch closed duringthe rendering operation of the cocker, a solenoid effective whenenergized for holding said steam vvalve open, signal means, a'controlcircuit'includswitching means held closedduring 'the-rendering operationfor retaining the said releasable means in motor Operating position andfor maintaining said solenoid energized, a second control circuitincluding said signal means and switching means held open during saidrendering operation, and a third control circuit including an immovableterminal mounted in said inner shell in insulated spaced relationthereto, the said terminal being so positioned that the space between itand the shell is spanned by continuously changing samples of saidmaterial being moved along by the said agitator blades, whereby the saidsamples conduct current between the terminal and said shell inaccordance with the moisture content of the samples, and means in thesaid third circuit responsive to the current flow therein correspondingto a predetermined moisture content of the material for effecting theopening of the said switching means in the first said circuit to therebyeffect the opening of said main switch and the deenergization of saidsolenoid whereby the said motor is stopped and the steam valve isclosed, and for effecting the closing of the said switching means in thesaid second circuit to close said second circuit and actuate said signalmeans.

5. The combination with a cooker containing a charge of material to berendered, having fixed inner and outer cylindrical shells with anannular space therebetween, a rotatable shaft centrally disposed withinsaid shells with agitator blades mounted thereon so as to Wipe aroundthe inner shell close by its bottom wall, Van electric motor for drivingsaid shaft, a power circuit connected to said motor, a main switch insaid power circuit, a fluid fiow connection between said annular spaceand a supply of steam, and a valve in said fiuid flow connection forcontrolling the fiow of steam therethrough, of control means responsiveto a predetermined condition of said material for stopping said motorand closing said steam valve when said predetermined condition of thematerial being rendered is reached; said control means comprising anauxiliary circuit which is closed upon the said main switch being closedin its run position; means in said auxiliary circuit for holding saidmotor switch closed in its run position and for holding said steam valveopen; a second auxiliary circuit normally open during the renderingoperation and capable upon being closed to effect the opening of thefirst said auxiliary circuit; and a third auxiliary circuit includingsaid inner shell and an immovable terminal fixed in the bottom wallthereof and insulated therefrom in such spaced relation thereto that thespace between said terminal and said inner shell is bridged bycontinuously changing samples of the said material as they are wipedacross said terminal by the said agitator blades whereby the moisture ofthe said samples conclucts the current fiow in said third circuitbetween said terminal and said shell, the saidv curi rent flow being indirect relation to said moisture content of said samples, and means insaid third auxiliary circuit responsive to the current flow reaching apredetermined amount corresponding to the end point of the renderingprocess to effect closure of the said second auxiliary circuit andthereby bring about the opening of the first Vsaid circuit whereby thesaid main switch is opened and the steam valve is closed.

6. The combination With a cooker containing a charge of material to berendered and having fixed inner and outer cylindrical shells with anannular space therebetween, piping connecting said annular space with asupply of steam and having a valve therein, a rotatableshaft "centrallydisposed within said shells with agitator blades thereon so as tofiwipearound the inner shell close by its bottom wall and a motor for drivingsaid shaft, of control apparatus for controlling the operation of saidValve and said motor comprising a control circuit for said motor withswitching means therein which When closed effects actuation of saidmotor, a solenoid connected with said valve and capable when energizedof holding said valve open, a second control circuit for energizing saidsolenoid and thereby holding said steam valve open and-having energizedrelay means therein effective on the switching means of the first saidcontrol circuit for holding the first said circuit closedV therebykeeping the motor in operation, and a third circuit includingconnections with-the inner shell and with an immovable terminal fixed inthe wall of said inner shell and insulated therefrom in spaced relationthereto so that continuously changing samples of the material beingrendered bridge the space between the terminal and said shell wherebythe moisture content of said samples conducts the current flow in saidthird circuit, the amount of said current fiow being directlyproportional to the moisture content of said samples, and a relay insaid third circuit which responds when said current fiow corresponds toa predetermined condition of the material to effect opening of theswitching means in the first said control circuit and the deenergizationof said solenoid thereby to stop said motor and close said valve. V w

7. The combination with a cooker containing a charge of material to berendered and having fixed inner and outer cylindrical shells with anannular space therebetween, piping connecting said annular space with asupply of steam and having a valve therein, a rotatable shaft centrallydisposed within said shells with agitator blades thereon so as to wipearound the inner shell close by its bottom wall and a motor for drivingsaid shaft, of control means for controlling the action of said valveand said motor comprising a control circuit for said motor withswitching means therein which when closed effects actuation of saidmotor, a solenoid connected with said valve and capable when energizedof holding said valve open, a second control circuit which is energizedWhen said switching means of the first said circuit is closed to effectenergization of said solenoid, means controlled by said second controlcircuit for holding the said switching means-of the first said controlcircuit closed, a switch in said lsecond circuit held closed while saidmotor is in operation, a third circuit including relay means capablewhen energized of opening said switch in said second circuit and therebydeenergizing said second circuit, and a fourth circuit having connectionwith the inner shell and with an insulated terminal fixed in and inspaced relation to the bottom of said inner shell so as to be contactedby the continually charging samples of said material wiped across it bythe said agitator blades, the said spaced relation being such that thesaid samples make simultaneous contact with the inner shell and theterminal whereby the moisture content of the samples acts as a conductorfor current fiow between the inner shell and the terminal, the saidcurrent flow being proportional to said. moisture content in nislsampltand means 111..,Si1lf0urth e11?- 17 cuit responsve to the current fiowtherein and actuated When the said current flow corresponds to apredetermined condition of the said material to effect energization ofsaid third circuit Whereby the relay means in said third circuitoperates to open the said closed switch of the said second circuit,thereby deenergizing the said second circuit and effecting the closingof said steam valve and the Stepping of said motor.

CHARLES J. IVIERRIMAN. ALFRED P. HUCHBERGER.

REFERENCES CITED The following references are of record in the file ofthis patent:

Number 18 UNITED STA I'ES PATENTS Name Date Powling Dec. 15, 1914 LaabsMay 24, 1927 McTavish Dec. 11, 1928 Halvorson et al. Oct. 10, 1933 WebbOct. 17, 1933 Fisher et al. Oct. 8, 1935 Elberty, Jr June 23, 1936Stephen Feb. 11, 1941 Preston Oct. 23, 1945

